Underground electromagnetic-pulse collaborative plugging device and technology

Abstract

The invention relates to the technical field of petroleum underground plugging, and discloses an underground electromagnetic-pulse collaborative plugging device and process. A cable connected with a ground power supply is arranged in a connecting shaft; the electric energy and temperature control mechanism comprises a first shell, and a temperature control system and an electric pulse generator which are arranged in the first shell; the temperature control system and the electric pulse generator are connected with the cable in the connecting shaft; the electromagnetic heating and alloy containing mechanism comprises a second shell, an electromagnetic heating part, an electric pulse part and a plugging alloy, the electromagnetic heating part, the electric pulse part and the plugging alloy are arranged in the second shell, the electromagnetic heating part is connected with the temperature control system, the electric pulse part is connected with the electric pulse generator, and an opening capable of enabling the plugging alloy to circulate is formed in the bottom end of the second shell; the soluble alloy plate is arranged at the opening of the bottom end of the second shell, the alloy structure can be uniform, and the formed metal-cement composite plugging structure has excellent long-term sealing stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil downhole plugging, in particular to a downhole electromagnetic-pulse synergistic plugging device and process. BACKGROUND

[0002] Global oil and gas resource development has led to a large number of oil and gas wells entering the end of service, and abandoned wells will cause environmental risks and safety hazards if not effectively plugged. The current mainstream cement plugging technology has technical bottlenecks such as high volume shrinkage, interface cracking risk, mechanical property degradation, and insufficient corrosion resistance, accompanied by high construction cost. The industry is currently developing new metal plugging materials represented by bismuth-based alloys, which can significantly shorten the length of the plugging section due to their solidification self-expansion characteristics, and have the advantages of improving construction efficiency and optimizing cost.

[0003] SnBi alloy has significant advantages as a downhole plugging material. The self-expansion effect generated during solidification can enhance the interface sealing and avoid the cracking problem of traditional cement. At the same time, the eutectic Sn-Bi alloy has a low melting point (138℃), which reduces the energy consumption of electromagnetic heating and reduces the risk of wellbore thermal damage.

[0004] The current electromagnetic heating system of thermite has significant technical defects: the high-temperature exothermic reaction at 2500℃ can easily cause potential damage to the wellbore structure, the reaction byproducts may form a weakened area at the plugging interface, and there are safety risks in the storage and transportation of thermite.

[0005] Electromagnetic heating is a non-contact heating technology that uses alternating magnetic fields to directly induce eddy currents in conductive materials and convert them into heat energy. When high-frequency alternating current passes through the coil, a rapidly changing magnetic field is generated. The magnetic field penetrates the heated body and excites eddy currents and hysteresis losses in metals or conductive media, instantly converting electrical energy into heat energy, achieving uniform heating from the inside to the surface of the material. At the same time, using electric pulses for homogenization during downhole plugging can make the plugging alloy have more excellent high-temperature aging resistance, and its plugging performance is improved. The two sets of equipment share rectification, filtering, IGBT inverter, and coil hardware, without the need for additional power supply. After the combination of the two, electromagnetic heating is responsible for "uniform preheating", and electric pulses are responsible for "precise control", forming a "heat-electromagnetic-force" multi-physical field coupling, which retains the efficiency of electromagnetic heating and introduces the non-equilibrium processing advantages of electric pulses. It is suitable for the rapid melting and organization optimization of downhole plugging metals. The whole process does not need open fire or heat conduction medium, the heating rate and power can be precisely controlled in milliseconds, and it is energy-efficient, clean and pollution-free.

[0006] Compared with the downhole heating using aluminum thermit, the electromagnetic-pulse cooperative downhole metal plugging device and process ensure the melt homogenization, solve the solidification segregation problem of high-bismuth alloy, and do not need combustion heat release, avoid the generation of toxic and harmful products such as carbon monoxide and smoke, and are safer in operation; the energy is transmitted by contactless coupling of electric-magnetic-thermal, the heating rate and power can be accurately controlled in real time, and the disadvantages of one-time violent heat release of aluminum thermit, easy over-temperature and the like are avoided; there is no consumable reagent, the process of frequent replacement of reagent and cleaning of residues is saved, the equipment can be repeatedly used, the operation cost is lower, and the plugging performance is more excellent.

[0007] Therefore, it is urgent to develop a new controllable electromagnetic heating system and develop a full-process safe plugging process, develop a special device for realizing microstructure homogenization of alloy and a supporting forming process, and break through the existing technical bottleneck. SUMMARY

[0008] The purpose of the present application is to provide a downhole electromagnetic-pulse cooperative plugging device and process, which aims to solve or improve at least one of the above technical problems.

[0009] To achieve the above purpose, the present application provides the following scheme: the present application provides a downhole electromagnetic-pulse cooperative plugging device, comprising:

[0010] A connecting shaft in which a cable connected to a ground power supply is arranged;

[0011] An electric energy and temperature control mechanism comprising a first shell, a temperature control system and an electric pulse generator arranged in the first shell, the first shell being connected to the connecting shaft, and the temperature control system and the electric pulse generator being connected to the cable in the connecting shaft;

[0012] An electromagnetic heating and alloy containing mechanism comprising a second shell, an electromagnetic heating part, an electric pulse part and a plugging alloy arranged in the second shell, the second shell being connected to the first shell, the electromagnetic heating part being connected to the temperature control system, the electric pulse part being connected to the electric pulse generator, and the second shell being provided with an opening at the bottom end for allowing the plugging alloy to flow through;

[0013] A soluble alloy plate arranged at the opening at the bottom end of the second shell.

[0014] Optionally, the plugging alloy is a Bi-Sn alloy material, wherein the mass percentage of Sn is 42%, and the mass percentage of Bi metal is 58%.

[0015] Optionally, the electric pulse part comprises a plurality of pulse heads with variable voltage and frequency.

[0016] Optionally, the electromagnetic heating part comprises a third shell and electromagnetic heating coils spirally arranged on the sidewall of the third shell, the third shell is connected in the inner cavity of the second shell, the bottom opening of the third shell is opposite to the opening of the bottom end of the second shell, and the sealing alloy is arranged in the third shell.

[0017] Optionally, a first temperature sensor is arranged on the sidewall of the second shell.

[0018] Optionally, a second temperature sensor is arranged on the sidewall of the third shell.

[0019] Optionally, the working temperature of the electromagnetic heating part is 138-300 DEG C.

[0020] Optionally, the electric pulse generator is alternating current, and the voltage range is 20-60 V.

[0021] Optionally, the melting point of the soluble alloy plate is lower than that of the sealing alloy.

[0022] The application also provides a downhole electromagnetic-pulse synergistic sealing process, comprising the following steps:

[0023] A bridge plug is arranged in a target layer section in a well and a cement plug is cast;

[0024] The device is lowered to the top of the cement plug through the connecting shaft;

[0025] The electromagnetic heating part and the electric pulse part are started, so that the soluble alloy plate and the sealing alloy are melted in sequence, the molten alloy formed by melting of the sealing alloy falls above the cement plug through the opening of the bottom end of the second shell, and a metal sealing layer is formed after cooling;

[0026] The device is pulled out as a whole through the connecting shaft.

[0027] The application discloses the following technical effects:

[0028] The application melts the alloy by electromagnetic field heating, simultaneously processes the alloy melt by electric pulse, and then makes the alloy uniform, so that the metal-cement composite sealing structure formed has excellent long-term sealing stability.

[0029] The electromagnetic heating temperature is accurately controllable, and the thermal damage of 2500 DEG C ultra-high temperature of the aluminum thermate to the wellbore is avoided.

[0030] The application has no combustion by-products in the whole process, and guarantees the integrity of the sealing interface.

[0031] The application improves operation efficiency and reduces comprehensive cost, and the metal-cement composite sealing structure formed has excellent long-term sealing stability. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of the application illustrated in the drawings are intended to explain the aspects of the present application and are not limiting of the present application. In the drawings:

[0033] Figure 1 is a structural schematic diagram of the present application;

[0034] Figure 2 is a schematic diagram of the plugging alloy in a plugged state of the present application;

[0035] Figure 3 is a flow chart of the present application;

[0036] Figure 4 is a comparative electron micrograph of the pulse structure after applying different voltages during solidification of the Sn58Bi alloy of the present application;

[0037] Figure 5 is a statistical diagram of the interval of the pulse structure after applying different voltages during solidification of the plugging alloy of the present application.

[0038] In the figure: 1, connecting shaft; 2, electric energy and temperature control mechanism; 21, temperature control system; 22, electric pulse generator; 23, first shell; 3, electromagnetic heating and alloy containing mechanism; 31, third shell; 32, second shell; 33, pulse head; 34, electromagnetic heating coil; 35, second temperature sensor; 36, first temperature sensor; 37, plugging alloy; 4, soluble alloy plate; 5, cement plug; 6, bridge plug. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0040] In order to make the above objectives, characteristics and advantages of the present application more apparent, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] With reference to Figures 1-5 , the present application provides a downhole electromagnetic-pulse synergistic plugging device, comprising:

[0042] Connecting shaft 1, built-in cable connected to the ground power supply;

[0043] The electric energy and temperature control mechanism 2 comprises a first shell 23, a temperature control system 21 and an electric pulse generator 22 arranged in the first shell 23, and the first shell 23 is connected with the connecting shaft 1, and the temperature control system 21 and the electric pulse generator 22 are connected with the electric cable in the connecting shaft 1;

[0044] The electromagnetic heating and alloy containing mechanism 3 comprises a second shell 32, an electromagnetic heating part, an electric pulse part and a sealing alloy 37 arranged in the second shell 32, and the second shell 32 is connected with the first shell 23, the electromagnetic heating part is connected with the temperature control system 21, the electric pulse part is connected with the electric pulse generator 22, and the second shell 32 is provided with an opening at the bottom end, and the sealing alloy 37 can flow through the opening;

[0045] The soluble alloy plate 4 is arranged at the opening at the bottom end of the second shell 32.

[0046] The temperature control system 21 is used for controlling the electromagnetic heating part to heat the sealing alloy 37 to be in a molten state.

[0047] The electric pulse generator 22 is used for controlling the electric pulse part to oscillate the sealing alloy 37 in the molten state.

[0048] By accurately controlling the electromagnetic heating power and the pulse parameters, after the soluble alloy plate 4 is melted, the electromagnetic heating part and the electric pulse part jointly generate controllable joule heat to melt the Sn58Bi sealing alloy 37, and the high-frequency electromagnetic field applied by the electric pulse part is supplemented by electromagnetic oscillation and electronic wind force effect, so that the sealing alloy 37 is in a molten state with uniform distribution of elements, the segregation of the melt caused by the density difference of Bi / Sn is effectively overcome, and uniform distribution of alloy elements is realized; finally, the molten and homogenized alloy is accurately injected into the upper part of the cement plug 5 through the opening at the bottom end of the second shell 32, and a dense and defect-free metal sealing layer is formed after cooling.

[0049] In an embodiment of the present application, the sealing alloy 37 is a Bi-Sn alloy material, wherein the mass percentage of Sn is 42%, and the mass percentage of Bi metal is 58%.

[0050] In an embodiment of the present application, the electric pulse part comprises a plurality of pulse heads 33 with variable voltage and frequency.

[0051] In an embodiment of the present application, the electromagnetic heating part comprises a third shell 31 and an electromagnetic heating coil 34 spirally arranged on the side wall of the third shell 31, the third shell 31 is connected in the inner cavity of the second shell 32, the bottom opening of the third shell 31 is open and opposite to the opening at the bottom end of the second shell 32, and the third shell 31 is provided with the sealing alloy 37.

[0052] Further, a plurality of first constraint holes are formed in the middle of the top wall of the third shell 31 for mounting a plurality of pulse heads 33, and a plurality of second constraint holes are formed in the side wall of the third shell 31 in a circumferential direction for mounting the electromagnetic heating coil 34.

[0053] In an embodiment of the present application, a first temperature sensor 36 is arranged on the side wall of the second shell 32.

[0054] In an embodiment of the present application, a second temperature sensor 35 is arranged on the side wall of the third shell 31.

[0055] In an embodiment of the present application, the working temperature of the electromagnetic heating part is 138-300 DEG C.

[0056] In an embodiment of the present application, the electric pulse generator 22 is an alternating current with a voltage range of 20-60 V.

[0057] The alternating current pulse significantly promotes the composition homogenization of SnBi alloy and improves the downhole metal plugging efficiency through the synergistic effect of the electromigration effect and the thermal effect. The electronic wind force driven by the high-density electron flow drives the directional migration of Sn and Bi atoms, and the Joule heat reduces the diffusion potential barrier, accelerates the interdiffusion of solute atoms and relieves the segregation; at the same time, the alternating electric field weakens the stability of the segregated phase through electromagnetic oscillation, further optimizing the composition distribution. Compared with direct current, the periodic commutation of alternating current avoids heat accumulation and migration imbalance, and its non-thermal dominant mechanism is effectively improved at low energy consumption, especially suitable for the homogenization regulation of low-melting-point SnBi alloy, which is the key to solving the downhole filling problem.

[0058] In an embodiment of the present application, the melting point of the soluble alloy plate 4 is lower than that of the plugging alloy 37.

[0059] The present application also provides a downhole electromagnetic-pulse synergistic plugging process, comprising the following steps:

[0060] A bridge plug 6 is arranged at a target layer section in a well and a cement plug 5 is poured, and after the cement plug 5 is fixed;

[0061] The device is lowered as a whole to the top of the cement plug 5 through the connecting shaft 1;

[0062] The electromagnetic heating part and the electric pulse part are started to make the soluble alloy plate 4 and the plugging alloy 37 melt in turn, and the molten alloy formed by the melting of the plugging alloy 37 falls above the cement plug 5 through the opening at the bottom end of the second shell 32, and forms a metal plugging layer after cooling;

[0063] The device is taken out as a whole through the connecting shaft 1.

[0064] Compared with the traditional use of thermite combustion to melt the alloy, the device uses the electromagnetic heating mode to make the temperature control easier, will not cause damage to the wellbore, and will not produce oxides or other by-products to affect the sealing performance. The Sn58Bi sealing alloy treated by electromagnetic heating and electric pulse has more excellent high-temperature aging resistance, and the sealing performance is improved.

[0065] The microstructure of Sn58Bi sealing alloy after 0 / 20 / 40 / 60V electric pulse treatment and 80℃ aging for 1024h is shown in Figure 4 When no electric pulse is applied, the alloy plug has uneven distribution of elements and organization after aging, as shown in Figure 4 (a). After 20V, 40V and 60V electric pulse treatment, the aging organization of Sn58Bi alloy plug is obviously refined, and the uniformity is greatly improved, as shown in Figure 4 (b)-(d). The compression strength test is carried out on the alloy plug treated by electric pulse, and the result is shown in Figure 5 Compared with the untreated alloy plug, the Sn58Bi alloy plug treated by electric pulse has more excellent compression strength, which shows that the electric pulse treatment can improve the sealing effect of the alloy plug.

[0066] In the description of the present application, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0067] The above-described embodiments are only preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope of the present application as defined by the claims.

Claims

1. A downhole electromagnetic-pulse coordinated plugging device, characterized in that, include: Connecting shaft (1), with a built-in cable for connecting to ground power; The power and temperature control mechanism (2) includes a first housing (23) and a temperature control system (21) and an electric pulse generator (22) disposed in the first housing (23). The first housing (23) is connected to the connecting shaft (1). The temperature control system (21) and the electric pulse generator (22) are both connected to the cable in the connecting shaft (1). The electromagnetic heating and alloy containing mechanism (3) includes a second housing (32) and an electromagnetic heating part, an electric pulse part and a sealing alloy (37) disposed in the second housing (32). The second housing (32) is connected to the first housing (23). The electromagnetic heating part is connected to the temperature control system (21). The electric pulse part is connected to the electric pulse generator (22). The bottom end of the second housing (32) is provided with an opening that allows the sealing alloy (37) to flow through. A soluble alloy plate (4) is disposed at the opening at the bottom end of the second housing (32).

2. The downhole electromagnetic-pulse coordinated plugging device according to claim 1, characterized in that, The sealing alloy (37) is a Bi-Sn alloy material, wherein Sn accounts for 42% by mass and Bi metal accounts for 58% by mass.

3. The downhole electromagnetic-pulse coordinated plugging device according to claim 1, characterized in that, The electrical pulse unit includes multiple pulse heads (33) with variable voltage and frequency.

4. The downhole electromagnetic-pulse coordinated plugging device according to claim 1, characterized in that, The electromagnetic heating part includes a third housing (31) and an electromagnetic heating coil (34) spirally disposed on the side wall of the third housing (31). The third housing (31) is connected to the inner cavity of the second housing (32). The bottom opening of the third housing (31) is open and opposite to the opening at the bottom end of the second housing (32). The sealing alloy (37) is disposed inside the third housing (31).

5. The downhole electromagnetic-pulse coordinated plugging device according to claim 1, characterized in that, A first temperature sensor (36) is provided on the side wall of the second housing (32).

6. The downhole electromagnetic-pulse coordinated plugging device according to claim 4, characterized in that, A second temperature sensor (35) is provided on the side wall of the third housing (31).

7. The downhole electromagnetic-pulse coordinated plugging device according to claim 1, characterized in that, The operating temperature of the electromagnetic heating element is 138-300℃.

8. The downhole electromagnetic-pulse coordinated plugging device according to claim 1, characterized in that, The electrical pulse generator (22) is AC, with a voltage range of 20-60V.

9. A downhole electromagnetic-pulse coordinated plugging device according to claim 1, characterized in that, The melting point of the soluble alloy plate (4) is lower than that of the sealing alloy (37).

10. A downhole electromagnetic-pulse coordinated plugging process, based on the downhole electromagnetic-pulse coordinated plugging device according to any one of claims 1-9, characterized in that, Includes the following steps: A bridge plug (6) is installed in the target formation downhole and a cement plug (5) is poured. The entire device is lowered to the top of the cement plug (5) via the connecting shaft (1); The electromagnetic heating unit and the electric pulse unit are activated, causing the soluble alloy plate (4) and the sealing alloy (37) to melt in sequence. The molten alloy formed by the melting of the sealing alloy (37) falls through the opening at the bottom of the second shell (32) to the top of the cement plug (5), and forms a metal sealing layer after cooling. The entire device is lifted out via the connecting shaft (1).

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